摘要：降雨条件下坡内渗流和坡面径流产生的山地灾害链式反应已经逐渐成为国内外研究的重点,但由于认识的局限性,坡内渗流、坡面径流、坡面侵蚀、泥石流启动和滑坡等过程往往被人为分割成几个部分分别加以研究,导致对降雨而引起的山地灾害各因素之间的有机联系缺乏深刻的认识。本文采用Richards方程和Saint-Venant方程组分别描述坡体入渗和坡面径流问题,用有限体积法(FVM)对以上问题编写Matlab程序求解,并在每一个时间步对Richards方程和圣维南方程进行数值耦合,得到降雨条件下的坡体入渗和坡面径流耦合模型。通过算例,表明基本规律符合现实情况,说明了所建立耦合模型的可靠性。

摘要：Based on the elastic thin plate theory,the main law of the ore roof failure was analyzed and the formula of the ore roof thickness was *** results show that the tensile stress in the roof center accounts for the roof *** to the limit failure conditions of the point,the formula of the ore roof thickness was *** No.10 stope of a bauxite mine as an engineering case,the optimal thickness of the ore roof was 0.36 *** safety factor was taken as 1.3,therefore the design thickness was 0.5 *** the whole industrial test process,the dynamic alarm devices did not start the alarm and the ore roof was not *** with other stopes under similar conditions,its thickness was reduced by 0.1-0.3 *** recovery rate of the ore roof was increased by 16.7%-37.5%.

摘要：美国和苏联现有的舱外载人机动装置(Manned Maneuvering Unit,MMU)推进系统设计均采用两套独立系统互为备份的方式,主系统故障后可以启动备用系统,但备用系统故障则无应对方案,因此制约航天员的安全性和舱外活动能力。文章在常规主备份推进模式基础上提出了应急推进模式,备份推进器发生故障后,根据失效发动机组相对位置关系采用不同应急策略,剩余有效推进器通过联合控制的方式保证航天员六自由度控制。经过可行性分析和仿真计算,证明了应急模式下MMU推进能力有一定降低,但能够为航天员返回提供动力,应急推进模式具有可行性。

摘要：《绿野仙踪》里的女巫其实不是坏人。每年万圣节,她都会骑着扫帚给小朋友们发糖果呢!